Preparation of Ga₂O₃ thin film solar-blind photodetectors based on mixed-phase structure by pulsed laser deposition

Gallium oxide (Ga₂O₃) thin films were deposited on a-Al₂O₃ ($11\overline{2}0)$ substrates by pulsed laser deposition (PLD) with different oxygen pressures at 650 °C. By reducing the oxygen pressure, mixed-phase Ga₂O₃ films with α and β phases can be obtained, and on the basis of this, mixed-phase Ga₂O₃ thin film solar-blind photodetectors (SBPDs) were prepared. Comparing the responsivities of the mixed-phase Ga₂O₃ SBPDs and the single β-Ga₂O₃ SBPDs at a bias voltage of 25 V, it is found that the former has a maximum responsivity of approximately 12 A/W, which is approximately two orders of magnitude larger than that of the latter. This result shows that the mixed-phase structure of Ga₂O₃ thin films can be used to prepare high-responsivity SBPDs. Moreover, the cause of this phenomenon was investigated, which will provide a feasible way to improve the responsivity of Ga₂O₃ thin film SBPDs. (special topic)